J.s. Mohamed Ali

International Islamic University Malaysia | iium · Department of Mechanical and Aerospace Engineering

Most engineering technologies, gadgets, and systems have been developed around the use of sophisticated materials. Composite laminates have found widespread application in various significant and innovative industries, such as aviation, maritime transportation, automobiles, and civil engineering. Recent studies have revealed that composite material...

Buckling analysis of thin-walled structures is essential to ensure their structural integrity under various loading conditions. The study aims to analyse buckling in thin-walled structures, particularly a C-section channel, under different loads, considering cases with and without holes, using FEM. It investigates hole impact on buckling, critical...

This paper presents a finite element analysis to model and analyze composite laminated beams with distributed piezoelectric actuators attached to the top and bottom surfaces considering nonlinear constitutive equations under a high electric field. The static response is presented for piezoelectric composite laminated beam using higher order electri...

Citation: Aabid, A.; Ibrahim, Y.E.; Hrairi, M.; Ali, J.S.M. Optimization of Structural Damage Repair with Single and Double-Sided Composite Patches through the Finite Element Analysis and Taguchi Method. Materials 2023, 16, 1581. https:// Abstract: Over the last four decades, numerous studies have been conducted on the use of bonded composite repai...

In aviation history, accidents during landing are more frequent compared to other phases of flight and in most cases the aircraft is forced to make an emergency belly landing when landing gear malfunctions. This study aims to analyse the energy absorption of a typical composite aircraft fuselage section under such crash belly landing. A finite elem...

Piezoelectric material transducers can work as an actuator or sensor. Generally, the actuator will be used to repair the structure, and the sensor will be used to find the health condition. In the last two decades, piezoelectric actuators have shown the capacity to lower and control the shear stress concentration and joint edge peel in adhesively b...

Computational Fluid Dynamics analysis was used to study the effect of expansion level in a suddenly expanded flow for a converging-diverging nozzle expanded to the duct of larger diameter at supersonic Mach number. Parameters include the nozzle pressure ratio (NPR), L/D ratio, and area ratio. The model of the converging-diverging (C-D) nozzle sudde...

Aircraft structures are made of thin-walled structures as it provides higher stiffness to weight ratio compared to solid sections, but it is prone to buckling due to its low stiffness and slenderness of the individual element. One of the types of buckling that can impact the integrity of a thin-walled beam is lateral torsional buckling which is cau...

In the present study, the base pressure variations induced by the presence of a cavity, known to have a strong influence of the behaviour of supersonic projectiles, are investigated through numerical solution of the balance equations for mass, momentum, and energy. An area ratio of four is considered and numerical simulations are carried out at Mac...

In structural engineering, thin-walled structures play an important role in the design of the lightweight structural model. It carries different loading conditions when it exists in any model, and it is designed with thin plates or thin shells. Penetrating thin-walled structures with different kinds of holes can decrease their weight and facilitate...

The paper aims at reviewing the modeling of piezoelectric laminated structures for stress distribution, vibration and noise control, shape control, health monitoring, and energy harvesting. Accurate modeling of piezoelectric laminates using linear and non-linear modeling techniques is essential at the high and low electric fields. The review is don...

In aerospace engineering applications, lightweight material structures are considered to perform difficult service conditions and afford energy efficiency. Therefore, composite materials have gained popularity due to their light weights and high performances in structural design. Mechanical loads and environmental conditions primarily create damage...

Take-off and landing are the critical phases of an aircraft flight where there is a high demand of lift force at the lowest stalling speed of aircraft. Use of different techniques to increase the lift force during these phases of flight is one of the prime objectives in the design of an aircraft wing. Delaying and eliminating flow separation using...

Energy is the core requirement for all sectors to operate efficiently and successfully. Many sectors in Malaysia progressively uses more energy as its economy grows rapidly. The main four energy expending sectors are Industry, transportation, business and private structures. Decisively, business and private structures contribute about one third of...

The paper illustrates the review on the optimizations studies of HVAC systems based on three main methods – HVAC operational variables optimization, optimization of control parameters in HVAC system and parameter optimization in building models. For the HVAC system’s operational variables, the optimization process is based on the common and prescie...

Ribs in aircraft wings maintain the airfoil shape of the wing under aerodynamic loads and also support the resulting bending and shear loads that act on the wing. Aircrafts are designed for least weight and hence the wings are made of hollow torsion box and the ribs are designed with cutouts to reduce the weight of the aircraft structure. These cut...

Aircraft wings are designed with very low factor of safety to keep the aircraft weight minimum. Thus, for safe design of wings, stress analysis should be carried out under accurately estimated aerodynamic loads and this can be achieved only through coupled fluid-structure analysis. Moreover, modern aircraft wings are made of laminated composite str...

A Review about use of Higher order Non-linear Piezoelectric effect for accurate modeling in stress distribution, vibration and noise control, shape control, health monitoring, and energy harvesting.

In this work, a study has been conducted to observe the influence of fuel weight distribution on the flutter characteristics of a high aspect ratio swept wing. In this paper, B777-200 wing model having a 34º sweptback angle is used as a baseline and two other models with the swept angles of 0º (straight wing) and 30º (forward swept) are considered...

The design and sizing of adhesives used for bonding of two or more similar/dissimilar materials in aerospace and automobile structural engineering studies have always been important. A vast number of studies have reported via experimental, numerical, and analytical methods of lap joint system with adhesive bonding. Optimization studies of the adhes...

Active repair of a damaged structure using piezoelectric (PZT) actuators has played a significant role during the last two decades in reducing crack damage propagation in structures due to its electro-mechanical effect. Similarly, passive repair of damaged structures using composite materials has been widely used in recent years, and it has been di...

An educational software has been developed for stress analysis of laminated composites. The software can be used to study both micro- and macro-mechanics analysis of a lamina as well as a laminate. The software can also be used for the failure analysis of laminates, and hence can be useful for the design of composite laminates for given loading con...

The repair of aircraft structures using composite material patches are well known in aerospace industries. In the present work composite patch bonded with a superglue over a cracked rectangular plate under uniform uniaxial tensile stress is considered. A three-dimensional finite element method was used to define the stress intensity factor for a re...

In this work, the combined effect of moisture and temperature on the bending behavior of simply supported anisotropic cylindrical shells has been investigated. Initially three dimensional equilibrium equations of thermoelasticity, simplified to the case of a generalized plane strain deformations in the axial direction are solved analytically for an...

Crack propagation until fracture is an important criterion to predict a structure‘s service life. In order to increase the latter, the cracked component needs to be repaired or replaced. In the present study, a finite element analysis has been carried out to investigate the effects of adhesive thickness, patch thickness and crack length on the pass...

The blunt base either in the front or at the rear portion of the vehicles is prevalent and is found in railways where the front and rear portions the coaches are blunt, which results in zero velocity and hence the stagnation pressure, which is undesirable. The aim of this study is to investigate the effect of the splitter plate on the wake control...

This paper investigates the aerodynamics of a circular plan form wing at high Reynolds numbers numerically. Commercial software STAR-CCM+ has been used for the study. The numerical results were presented in terms of flow visualization, pressure over the wing, velocity contour and streamlines, lift and drag coefficients for angle of attacks ranging...

In this paper, shape control of composite plates using piezoelectric actuators is being investigated. The goal of this study was to see how composite plates behave when they are integrated with piezoelectric actuators. Modelling and simulation were done using COMSOL Multiphysics software and results were validated using previously published studies...

Aerospace structures such as fuselage and wings are made of typical thin-walled closed sections and the detailed stress analysis of such closed thin-walled structures can be tedious and time consuming due to its statically indeterminate nature of the problem. In the present work, an educational software for the stress analysis of such non-idealized...

The aerodynamic drag on trucks can be reduced by use of active and passive techniques. In this work a passive method of using a cab-extender that is attached to the rear of the tractor is attempted. This cab-extender will help in reducing the drag force that act on the truck by minimizing the gap between the tractor and trailer. In this study, a tr...

Aerospace structures are typically semi-monocoque structures that are made up of thin-walled closed section reinforced with stiffeners. Stress analysis of such closed thin-walled structures which are statically indeterminate is tedious and time consuming. An educational software which can aid students in carrying out stress analysis of such idealiz...

Cut-outs on aircraft wings are unavoidable due to the placement of fuel tanks and retraction of landing gear inside the wing. The stresses acting on an aircraft wing will deviate substantially before and after a cut-out is made and therefore it is crucial to perform stress analysis in an aircraft wing in order to ensure that the wing structure will...

Hybrid buoyant aircraft are new to the arena of air travel. They have the potential to boost the industry by leveraging new emerging lighter-than-air (LTA) and heavier-than-air (HTA) technologies. Hybrid buoyant aircraft are possible substitutes for jet and turbo-propeller aircraft currently utilized in aviation, and this manuscript is a country-sp...

Stitching has proven to be an effective reinforcement for improving through-thickness (out-of-plane) mechanical properties with the incorporation of z-direction reinforcements of synthestic fiber. There are drawbacks to stitching as it may cause focal stress concentration, and fiber misalignment and breakage, but at the same time, it can also impro...

In this work, initially the effect of nose shape on the drag characteristics of a high speed train is studied. Then the influence of cross winds on the aerodynamics and hence the stability of such modern high speed trains is analyzed. CFD analysis was conducted using STAR-CCM+ on trains with different features and important aerodynamic coefficients...

This paper focuses on finding the optimal location for a piezoelectric patch for minimizing the settling time of an excited isotropic and orthotropic plate. COMSOL Multiphysics has been used to design and model the plate with PID controller. Classical Optimization tool called Parametric Sweep has been used to achieve the objective of the experiment...

Natural, short, untreated and randomly oriented oil palm empty fruit bunch fiber reinforced epoxy composites were manufactured using vacuum bagging technique with 20% fiber volume composition. The performance of the composite was evaluated as an alternative to synthetic or conventional reinforced composites. Tensile properties such as tensile stren...

Purpose Realistic data bank of aerodynamic and stability derivatives is still missing for hybrid buoyant aerial vehicles. Such vehicles take-off and land similar to an aircraft with their partial weight balanced by the aerostatic lift. The purpose of this paper is to use wind tunnel testing for a better understanding of the aerodynamic and static...

All buoyant and hybrid buoyant aerial vehicles have directional stability issues at low speed. Electric trimmers are one of the potential solutions for controlling the yaw motion of such vehicles in which partial lift is obtained from the wings. However, available propeller disk area of such trimmers is limited due to small surface area of the vert...

It is well known that hydrogen has less undesirable exhaust emissions as compared with other types of liquid fuels. It can be used as an alternative fuel for a hybrid buoyant aircraft in which half of the gross takeoff weight is balanced by the aerostatic lift. In the present study, weight advantage of liquid hydrogen as an ideal fuel has been expl...

The current data bank of operational empty mass fraction of airships is based on available data obtained from existing and historical airships. For any design related activity, regression analysis on existing data bank of airships will not be able to provide the true picture of mass fractions of hybrid airships. This situation becomes more critical...

Munk-Multhop's method is usually used for estimation of pitching moment of fuselage of conventional aircraft but application of the same for hybrid lifting fuselage had not been earlier explored. CFD methods can also be applied for the said purpose but it is difficult to separate out the portion of the moment caused by the fuselage, since the wing...

Wind Tunnel Testing on a subscaled model of a winged hybrid airship requires a faithful reproduction of all geometric details of actual airship. Due to huge volume of hull, geometrical parameters of such airships are quite different from that of an aircraft. In this article, a scheme for designing such models is described alongwith a review of diff...

Solutions within the framework of linear uncoupled thermoelasticity, are presented here for simply supported infinitely long anisotropic cylindrical shell panels subjected to thermal gradient. Benchmark numerical results in the form of displacements and stresses are tabulated for certain angle-ply layup useful for the assessment of improved shell t...

LEADME (Laminate Analysis and Design Made Easy), an educational software useful for the analysis and design of laminated composite structure has been developed. The software encompasses both the micro and macro mechanics analysis of lamina and laminate. The highlight of this software is that, apart from usual laminate analysis, the software is capa...

The combined effect of moisture and temperature on the bending behaviour of simply supported cross ply composite laminated shells has been investigated. A 13 term accurate higher order shear deformation theory with zigzag function is used in this analysis in which the effects of transverse shear deformation are taken into account. The results are p...

An educational software which can aid students in stress analysis of thin wall open sections made of composite material has been developed. The software enables students to easily calculate stresses of thin wall open section and evaluate the stresses in each ply. Results obtained through this software have been validated against ANSYS V14. The soft...

Mirrorless cars are the conceptual cars in which the mirrors which are used as a visual aid for safe driving are replaced with camera and LCD screens thus making it totally mirrorless. These cars without mirror projections will result in clean external aerodynamics thereby reducing considerable amount of drag and hence offers a high potential to ac...

In the field of aviation, it is well known that a vehicle’s stability and takeoff flight segment are critical issues for a flight vehicle design. These problems become more critical for a hybrid buoyant aircraft which is concealed as an airship with huge volume of hull as compared with fuselage of a conventional aircraft. In the present work, these...

Use of low fidelity tools in designing subscale generic wind tunnel models is usually required to get first-hand knowledge about general trends of aerodynamic and stability parameters. Most of such tools are limited to well-defined conventional aircraft configurations. In the present work, aerodynamic and stability characteristics of a winged hybri...

The present study focuses on the sizing and aerodynamic contour design of a two-seater 1000 kg gross take-off mass winged hybrid airship. Unlike the conventional hybrid airships, which stay aloft and takeoff with the help of VTOL propulsion systems, a winged hybrid airship requires a certain speed to takeoff by utilizing lift coming from its aerody...

Numerical simulations play a dominant role in design of experiments to get first hand knowledge about the aerodynamic behavior before the beginning of wind tunnel testing. In the present work, the static longitudinal stability characteristics of a single lobe winged-hybrid airship are investigated with two different empennages. Based on the previou...

This paper works on the curvature composite structure for wing leading edge application using fabric carbon/epoxy material subjected to impact loading. At first stage, rigid spherical projectile and elliptical panel with were used. The impact testing has been carried out by varying the radius of curvature, the thickness of the panel and different s...

In this study, the effect of window opening on the drag characteristics of a car is investigated. This additional aerodynamic drag can considerably affect the performance of a car in terms of instability, noise and fuel consumption. Using a 3D car model, the effect of window opening on the drag characteristics was numerically studied using STAR-CCM...

In this study, numerical simulation of tubes of various cross section under axial compression is carried out using LS-DYNA. The effect of varying configurations of tube crosssection shape on the deformation response, collapse mode and energy absorption characteristics of tubes under quasi-static axial compression have been studied. The validation o...

An educational software which can aid students in stress analysis of idealized thin-walled open sections has been developed. The software enables students to select different cross-sections which may be subjected to bending, shear or torsional loads and evaluate the stresses on it. Results obtained through this software have been validated. The sof...

Buckling and crushing behaviour of hollow structure was studied through experiments and numerical simulation. The experimental material was a thin aluminium square tube (38 x 38, 1.2 mm thick). Quasi-static crushing load was applied using a Universal Testing Machine, Shimadzu Autograph (AG-X) series which uses TRAPEZIUMX software for control and da...

A stress analysis software based on MATLAB, Graphic user interface (GUI) has been developed. The developed software can be used to estimate load on a wing and to compute the stresses at any point along the span of the wing of a given aircraft. The generalized formulation allows performing stress analysis even for a multispar (multicell) wing. The s...

A new displacement-based higher order theory is presented here. The theory employs realistic displacement variations and is shown to be extremely accurate for even thick laminates and for any combination of mechanical and thermal loading. The importance of various higher-order terms in the proposed theory is discussed with reference to a specific n...

Solutions, within the framework of linear uncoupled thermoelasticity, are presented for certain problems of flexure of composite laminates. Benchmark numerical results, useful for the validation or otherwise of approximate laminate models, are tabulated. Finally, these results are used to examine the accuracy of the classical lamination theory base...